Temp Gauge

[FuptDuck]

69 Z/28 original 302 original console gauges.  Looking for suggestions to diagnose my temp gauge.  Within minutes of starting the car the temp gauge slowly swings all the way to the right and would indicate the car has reached a very high temperature although it has barely warmed up.  I see nothing to indicate the car has reached such a high temperature, nothing coming out of overflow tube.  Anti freeze level is correct, there are no leaks.  The original radiator has been re-cored within the last 100 miles.  I purchased the car in August and immediately did a firewall forward restoration and I don't recall if the gauge functioned properly prior to dis-assembly.   

[dale_z28]

Could you have a sensor installed that's meant to trigger an idiot light? Or just the wrong sensor for "your" temp gauge? Maybe they're calibrated...

[Kelley W King]

Until you figure it out drop by Harbor Freight and $20 bucks and change for a temp laser gun and verify your temps. Every tool box should have one anyway. No need to spend big bucks, one of the car mags tested several and found the Harbor unit as good as any.

[Mark]

does it continue to swing over to hot if the car is not running and cold, or just when it is running and starting to heat up?

[169INDY]

Could the swing to HOT indicate a high resistance or open (poor) ground?

The Gas gage swings way past Full when it has the above issues could the temp act the same?

When troubleshooting a friends 69 Chevelle w/ gage we built a variable resistor enclosure to simulate a functioning sender that we ground and hook up to the sender wire to simulate and test the entire circuit when troubleshooting gage performance.

Pic

[1971ls6]

It is not grounded, a ground wire runs from the metal gauge bracket to one of the rubber boot mounting screws, mine just did it last month